“You have heard that the ancients were told, ‘YOU SHALL NOT COMMIT MURDER’ and ‘Whoever commits murder shall be liable to the court.’
But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, ‘You good-for-nothing,’ shall be guilty before the supreme court; and whoever says, ‘You fool,’ shall be guilty enough to go into the fiery hell”. (Matthew 5:21-22)

The scribes and the Pharisees had a righteousness that was external, and Jesus was saying that you must have one which exceeds that…one which is internal. God is concerned about what you really are–not what you appear to be. It is the internal that is infinitely more important than the external. Whereas the righteousness of the scribes and the Pharisees was an external, ceremonial, ritualistic, hypocritical legalism, the righteousness that God demands is something internal. That has always been God’s concern.

Adapted from a message by John MacArthur “The Attitude Behind The Act”